Recovering spent alkali



' UNITED STATES PATENT OFFICE.

VICTOR G. BLOEDE, OF BALTIMORE, MARYLAND, ASSIGNOR OF ONE-HALF TO JOHN BANOROFT, OF \VILMINGTON, DELAWARE.

RECOVERING SPENT ALKALI.

SPECIFICATION formingpart of Letters Patent No. 403,869, dated May 21, 1889.

Application filed April 13,1888. Serial No. 270,553. (No specimens.)

T at whom it may concern: or alkaline state become almost wholly in- 'Be it known that I, VICTOR G. BLOEDE, a soluble and separate more or less completely citizen of the United States, residing at Baltiin the form of a sediment or precipitate. more, in the State of Maryland, have invented Now, if the acid used for such neutralization certain new and useful Processes forthe Utiliof the spent lye be one that can subsequently 5 5 zation and Recovery of Spent Alkaline Liqagain be rendered insoluble, separated, or exuors; and I do hereby declare that the followtracted from the alkaline base with Which it ing is afull, clear, and exact description of the has been caused to combine, it is evident that invention, which will enable others skilled in a ready means for the rehabilitation of such Io the art to which it appertains to make and alkaline liquors is presented. 60

use the same. Having now described the general princi- The object of my invention is the recovery ple upon which my process is based, I will or rehabilitation of spent or waste alkaline detail the methods I have already success liquors, as well as the production incidentally fully employed in practical work. of several valuable residuary products. Taking as a fair example the spent alkaline 65 In the process of scouring or boiling off liquors obtained as a now entirely useless reyarns and textile fabrics, as well as in many siduum in the scouring of yarns andtextile other branches of manufacture, alarge amount fabrics, these liquors, of a more or less deep of alkali is used, which alkali, after having red or brown color, usually mark from to 3 been more or less impregnated with fatty, Baum, and consist of caustic or carbonated 70 resinous, and coloring matter, is at the pressoda, as the case may be, (or a mixture of cut time allowed to go to waste. both,) in which the coloring-matter and fatty In the manufacture of wood fiber and other resinous bodies removed from the fiber are processes the nature of I which requires that held in solution in a state of saponification.

the alkali be of a considerable degree of con- These liquors, as they are expelled from the 75 centration, the recovery of the alkali in the keir or boiling-vessels, are in the execution spent liquor is now eifected by the evaporaof my process allowedto flow into any contion of said liquor and subsequent incinera- Venient tank or vessel, preferably provided tion:or oarbonization of the organic impurities with a mechanical agitator, and sufficient contained. This process,now exclusively emphosphoric acid is added to effect complete 80 ployed, is not, however, available for the utilineutralization, or until a faint acid reaction zation of all classes of liquors, in that the of the liquor results. The previously clear practicability of the evaporation process is liquor becomes turbid by this treatment, and limited to comparatively strong alkaline liqupon being allowed to remain at rest for a 3 5 uors, much stronger, indeed, than any that are short time nearly the entire organic matters 85 used for scouring or other similar purposes. previouslyheld in solution subside in the form The advantage of my improved process lies of a brownish precipitate or maybe removed in the fact that it is applicable to liquors of by filtration. This precipitate, consisting all degrees of cbncentration, even the weakest largely of fatty and resinous matters which liquor practically used being under this syshave been separated from their alkaline 9o tem capable of rehabilitation and reutilizasaponification through the neutralization by tion. the acid, is of some value, and by subsequent The principle of my process is based upon refining may be made to yield a grease suitthe fact that when alkaline liquors highly able for lubricating, soap-manufacture, and

charged with resinous, fatty, or other organic other mechanical purposes. After the com- 5 impuritiessuch as the liquors produced in plete subsidence of the precipitate just dethe scouring of yarns and textiles, soap-manm scribed the previously highly-colored solution facture, and in other branches of the arts will be found to have been greatly lightened are neutralized with an acid the impurities in color, varying from alight wine to a straw 5', 5o soluble in the liquor while it is in a caustic shade, and now consists, of course, of a solu- I00 tion of phosphate of soda or potash, as the case may be, Should the further destruction of the coloring-matter it contains be found necessary or desirable, it may readily be effected at this stage ofthe process by the addition of a small quantity of any of the known powerf-ul oxidizers-for instance, permanganate of potash or soda, nitric acid, or chlorine, or by treatmentwith bone or wood charcoal. In practice I give preference to the injection of a little chlorine into the liquor, which speedily and completely eliminates the residuary color in the solution. The neutral solution, after the subsidence of all sedimentary matter, is drawn into a second tank or receiver, preferably provided with a mechanical agitator, and to this clear solution is now added sufficient milk of caustic or carbonate of lime, or a mixture of both, to reab'sorb the combined acid contained in the solution and to leave the lime in slight excess.

after the subsidence of the phosphate of lime, may now be reused like fresh alkali for fur- ,ther scouring operations.

The phosphate of lime obtained as a resid uaryproduct may be utilized either by treat -ment with an equivalent quantityof sulphuric acid to produce an acid-phosphate fertilizer, or it is entirely decomposed with sulphuric acid in the known manner for the recovery and reuse of the phosphoric acid as such.

Most of the works producing spent alkaline liquors have appliances for the causti-cization of the soda from its carbonate, and the refuse or sludge resulting from this operation, and consisting of mixtures of carbonate and caustic lime more or-less charged with soda, now forms a very objectionable and expensive residuum. This in" my process is very profitably utilized as a precipitant for the phosphoric acids in the operation of recovery. By such use of the lime sludge it will be seen that a very complete utilization of all of the active agents is insured and the highest possible economy achieved. Finally, the fatty bodies contained in the sedimentary matter obtained in the neutralization of the alkaline liquors may be purified by melting and clarifying or in any other convenient way, and can then be utilized for a number of purposes.

What I claim as my invention is- The process herein described for the recovery or rehabilitation of spent alkaline liquors, consisting of the following steps: first, the saturation or supersaturation of said liquors with phosphoric acid, thereby effecting the precipitation of the fatty and coloring matters; second, decanting or filtering the liquor from the separated impurities; third, when found desirable, destroying the residuary color in the decanted liquor with chlorine or its equivalent, and, fourth, subjecting the clarified liquor to the action of lime, barium, or other equivalent compounds capable of entering into an insoluble combination with or extracting the phosphoric acid and liberating the soda or potash in an available form as carbonate or hydrate.

VICTOR cl BLOEDEr Witnesses:

WM. G. OSTENDORF, GEO. R. 'COMEGYS. 

